This invention relates generally to packaging coils of electrical cable, and more particularly to a method of and apparatus for automatically coiling and packaging a plurality of coils and for automatically identifying individual coils in which a fault exists.
In conventional methods of manufacturing packaged coils of non-metallic multi-conductor insulated building cable, a predetermined length of cable is coiled on a rotating mandrel of a coiling machine to form a finished coil or hank of cable. Either before or after coiling, the cable is tested in accordance with certain standard tests, such as electrical conductivity, cable size and insulation resistance, to determine whether the individual coils of the cable conform with approved standards, e.g., U.L. approved standards. One such test for electrical continuity is commonly known as a "bell" test and is normally conducted after the cable has been wound into a completed coil. To perform the "bell" test, an operator individually connects each conductor of the coil in series with a power source and an electrically energizable signalling means, such as a common door bell, electric lamp or the like. Thus, actuation of the signal means, i.e., an audible or visual signal, indicates electrical continuity of the conductor. After completion of the required tests, the individual coils are packaged for ultimate distribution to the consumer. It is apparent that the "bell" test alone requires considerable intervention of manual labor resulting in a substantial increase in the cost of the final product. Moreover, the "bell" test does not lend itself to high-speed, automatic production of packaged coils of multi-conductor electrical cable.
Machines are also known in the packaging art for automatically coiling predetermined lengths of wire and cable and for packaging the individual coils. In U.S. Pat. No. 2,914,897, for example, there is disclosed an apparatus for feeding a cable onto a packing sheet supported on a rotating coiling mandrel. A desired length of cable is wound onto the mandrel over a central portion of the packing sheet and the ends of the packing sheet are thereafter folded over the outer periphery of the coil circumference. While this apparatus is capable of automatically coiling and packaging successive lengths of cable severed from an elongated cable element continuously fed to the apparatus, there are provided no in-line fault detection devices for performing tests of the aforementioned parameters of conductor continuity, cable size and insulation resistance and for automatically identifying in which particular coil a fault exists.
Also known in the prior art are apparatus for continuously testing a running length of non-metallic cable for electrical continuity, however, so far as it is known, such apparatus have not heretofore been utilized in combination with automatic wire coiling and packaging machines. One of the problems associated with using such electrical continuity testers in combination with an automatic cable coiling and packaging machine is the difficulty of discriminating in which of the individually wound and packaged coils a continuity fault exists. Interrupting the operation of the machine to remove the defective portion of cable would, of course, result in considerable loss of time and would be particularly disadvantageous in the high-speed in-line production system contemplated by the present invention.